Unfolder-Based Single-Stage AC-AC Conversion System for Wireless Charging Applications

Wireless charging applications in electric vehicles are at the core of USU’s research at the Utah Power Electronics Lab. This AC-AC conversion system efficiently changes the frequencies from 60 Hz grid power to the higher frequencies normally used in wireless charging applications, combining power factor correction (PFC) with output voltage or output current control into one stage.

Problem

Conventional wireless power transfer converters use a two-stage approach with a PFC stage and an inverter stage. The limitations of the two-stage design are the need of bulky electrolytic DC-link capacitors and the hard switching operations of the PFC stage.

Solution

The single-stage converter created by USU researchers combines the PFC and inverter actions into a single stage. It has a lower grid-side filtering requirement compared to the conventional two-stage systems, and therefore has a higher power density. The single-stage converter also does not need any grid current sensing for PFC, and its total harmonic distortion is less than five percent. The single-stage system is advantageous over other converters in terms of grid current quality, filtering requirement, and system efficiency.

Benefits

A more efficient and potentially more compact module for wireless charging applications would be beneficial for charging electric vehicles.  

Applications

This single-stage converter can be applied in the electric vehicles market, either charging electric vehicles in a business setting or in the home. It could also be a part of EV charging stations.

Contact

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Questions about this technology including licensing availability can be directed to:

Alan Edwards, MA, JD
Manager, Technology Transfer Services
(435) 797-2328 alan.edwards@usu.edu

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USU ID C22006